This invention relates to a new process for the preparation of microcrystalline triacetylcellulose.
There is an increasing demand for microcrystalline triacetylcellulose, which is chiefly used as a chromatographic adsorbent. This material is particularly suitable for the chromatographic resolution of racemates, the substantial or complete separation of the racemic forms into the corresponding enantiomers by chromatography on microcrystalline triacetylcellulose being possible for a large number of chiral compounds in particular.
It is possible to prepare microcrystalline triacetylcellulose by a process described by G. Hesse and R. Hagel (Chromatographia 6, 277 (1973), Chromatographia 9, 62 (1976) and Liebigs Annalen der Chemie 996 (1976)). In this process, microcrystalline cellulose is acetylated under gentle conditions with acetic acid and acetic anhydride in the presence of an amount of perchloric acid as a catalyst. Although this process is suitable for the preparation of microcrystalline triacetylcellulose on a laboratory scale, it presents serious hazards on an industrial scale.
Perchloric acid yields extremely explosive mixtures with organic substances and is therefore subject to strict safety measures and restrictions in handling. Industrial preparation of microcrystalline triacetylcellulose by this process using perchloric acid is therefore either impossible, or possible only if rigorous and expensive safety measures are taken.